LIFE HISTORY PATTERNS LIFE HISTORY PATTERNS: is a genetically inherited pattern of resource allocation (= investment) to that optimizes the passing of genes to the next generation Growth Reproduction Respiration Feeding Mate Seeking Defense Growth Reproduction Respiration Feeding Mate Seeking Defense Different investment patterns FOR REST OF TERM – LIFE HISTORY PATTERNS: is a genetically inherited pattern of resource allocation to that optimizes the passing of genes to the next generation EGG AND SPERM PRODUCTION FERTILIZATION PATTERNS SPERM COMPETITION TYPES OF DEVELOPMENT LARVAL DISPERSAL STRATEGIES SETTLEMENT PATTERNS Spawing and Fertilization Evolution of Anisogamy Imagine some Precambrian creature G. Parker Produces undifferentiated gametes Fertilization Gametes produced come in a variety of sizes Large Number produced Medium Small Mitotic competence Size distribution of gametes produced Gamete size Number produced External fertilization Which ones are the most likely to produce offspring? Combinations Very high Very high Very high Very low Moderate Very high Moderate Low Low High Very low Very high Competence Frequency of contact After several generations Selected against Gamete size Number produced Anisogamy Spermatogenesis is the process by which spearmtids are produced from male germ cells via mitosis and meiosis Spermiogenesis is the final stage of spermatogenesis in which spermatids add tails and become motile FERTILIZATION TYPES OF SPERM AND EGG RELEASE AND FERTILIZATION 1. Broadcast spawners (= free spawners) -eggs and sperm are released into the water column - fertilization is external 2. Spermcast spawners -sperm are released into the water column and taken in by the female -fertilization is internal 3. Copulators -sperm placed in the body of the female usually with some intromittent orgtan -fertilization is internal SPAWNING 1. BROADCAST SPAWNING SPAWNING 1. BROADCAST SPAWNING Problems for broadcast spawners How does an animal ensure fertilization by dumping eggs and sperm in the open ocean? 1. Proximity 2. Timing 3. Currents 4. Sperm/egg contact Boradcast spawners suffer a dilution effect Quinn and Ackerman. 2011. Limnol Oceanogr. 2011: 176 Boradcast spawners suffer a dilution effect How to get around this problem 1. Proximity mussels oysters How to get around this problem 2. Timing and synchrony Haliotis asinina Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193 How to get around this problem 2. Timing and synchrony Haliotis asinina Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193 How to get around this problem 2. Timing and synchrony Haliotis asinina Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193 How to get around this problem 2. Timing and synchrony Haliotis asinina Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193 How to get around this problem 2. Timing and synchrony Haliotis asinina Conclusions (Counihan et al. 2001) 1. Spawning season is determined by water temperature 2. Precise time of spawning is influenced by tidal regime 3. Both sexes spawn in response to an evening high tide 4. Males spawn 19 mins before high tide: females 11 mins after 5. More animals spawn in presence of opposite sex. Counihan et al. 2001. Mar.Ecol.Prog.Ser.213:193 3. Currents 3. Currents Patterns of flow – move gametes unpredictably Advection – mean direction and velocity of a gamete cloud Diffusion –rate of gamete spreading Main problem – production of eddies (vortices) – unpredictable and ephemeral 2 é æ y2u2 z-h) u 2 ö Qu ( êexp- ç ÷ + exp c(x,y,z) = + 2 2 2 2 2 2 2 2 ÷ ç 2pa ya z u x êë 2a z u x ø è 2a y u x 2 æ y2u2 z-h) u 2 öù ( ç 2 2 2 + ÷ú 2 2 2 ÷ ç 2a u x 2a z u x øúû è y 3. Currents 4. Sperm-egg contact a. Dilution -is it sperm concentration or egg:sperm ratio? If sperm and egg are at similar concentrations -sperm :egg ratio is important Sperm:egg ratio important Sperm concentration is imporant Final problem Egg and sperm longevity Horseshoe crabs Sea urchins Sea stars Ascidians hydroids Sea urchins Sea stars Ascidians Sperm live less than a few hours Eggs live about 3x longer than sperm How can sperm and egg increase the chances of contact? a) Chemical attractants How can sperm and egg increase the chances of contact? a) Chemical attractants L- Tryptophan in abalone Tryptophan ‘cloud’ How can sperm and egg increase the chances of contact? b) Jelly coat Jelly coat increases the size of the egg and acts as a sperm‘trap’ Fertilization Spermcast spawning -mating “by releasing unpackaged spermatozoa to be dispersed to conspecifics where they fertilize eggs that have been retained by their originator.” Bishop and Pemberton.2006. Integr.Comp.Biol. 46:398 Fertilization Spermcast spawning most sponges many hydroids some corals (Cnidaria) some polychaetes (Annelida), some bivalve Mollusca, Entoprocta, some articulate Brachiopoda, all Ectoprocta, most or all pterobranchs(Hemichordata), most ascidians (Chordata: Tunicata) Fertilization Spermcast spawning In most spermcasters Sperm release Intake by female Fertilization and brooding Storage of sperm Release of competent larvae Fertilization Spermcast spawning Factors influencing spermcasters 1. Longevity of sperm Species Temperature Half life (h) Tunicate A 16.5 8 Ectoproct 12, 16, 18 1.2 Tunicate B 15 26.3 22 16.1 Retain ability to fertilize longer than free spawners Fertilization Spermcast spawning Factors influencing spermcasters 2. Conservation of energy Sperm release Sperm are inactive or periodically active Intake by ‘female’ Consequence: Fertilization can happen with fewer sperm at greater distance Sperm consistently active Fertilization Spermcast spawning Factors influencing spermcasters 3. Sperm storage -allows accumulation of a number of allosperm Celleporella hyalina - Several weeks Diplosoma listerianum - 7 weeks Fertilization Spermcast spawning Factors influencing spermcasters Diplosoma listerianum 4. Egg development Sperm release Intake by ‘female’ Celleporella hyalina Triggering of vitellogenesis Consequence: Investment in eggs is not wasted. Next time : Sperm Competition